California proved well up to the step up in grade as she claimed top honours in the Markel Insurance Fillies' Stakes at Goodwood.
A comfortable winner of an Ascot handicap three weeks ago, John Gosden's filly was testing the water at Group Three level for the first time in a race better known as the Lillie Langtry Stakes.
Robert Havlin had the 9-2 chance well-positioned throughout as stable companion Mill Springs adopted a pacesetting role.
There were plenty in with chances entering the final furlong, but it was California who saw out the one-mile-six-furlong trip best to score by a length from Tioga Pass.
Favourite Pamona travelled noticeably well for a long way but weakened quickly when coming under pressure.
Havlin said: "We knew she would appreciate the step up in trip. She was staying on well last time and she'd run over a mile and six furlongs before.
"She's really blossomed in the last month."
Gosden will now look towards the Doncaster St Leger meeting with the winner.
He said: "She's taken a bit of time this spring as it was cold and wet, but she's coming right now and we will head for the Park Hill at Doncaster.
"She's likes to get her toe in as she's by Azamour so (the rain) wasn't a problem to her."
California could clash again with Tioga Pass at Doncaster.
Oliver Cole, son and assistant of trainer Paul, said: "I said before she would run a cracking race and she has. She has run her best race ever.
"She's been training very well at home and I still don't think we've got to the bottom of her yet.
"I think we will win a Listed race with her but I think there is a Group race in her and she's getting better with age.
"We will go for the Park Hill with her and we may find a race in France in between."
Hugo Palmer may look further afield with Twitch in hope of a Group-race success.
He said: "She's run very well and we are delighted with her. We had the choice between this and the Chalice Stakes at Newmarket. She's already been placed three times in Listed races so we thought we'd have a go at this.
"When I lost sight of them, there was a danger I thought she might be last but when she came back into view she'd nearly finished second
"I would say she's probably slightly better over a mile and a half, she definitely wants to stay in fillies' company and there are plenty of options both here and abroad for her."
